A conventional exhaust gas recirculation system is equipped with a mechanical control system in which the recirculation rate of the exhaust gas is controlled in accordance with an engine parameter such as the pressure of the exhaust gas emitted from the exhaust port of the engine. In such a conventional exhaust gas system, the recirculation rate undesirably varies when the engine operates at a low speed, while the recirculation rate is higher than required when the engine operates at a high speed with low load. Further, it is difficult to maintain the high precision and accuracy of the exhaust gas control system for a long period of time since some of the elements used in the control system are exposed to the hot exhaust gases. These drawbacks of the conventional exhaust gas recirculation system will be discussed in detail hereinlater.